HYDROACOUSTICS
ANNUAL JOURNAL |
START | NEW VOL 20 | SEARCH | STATISTICS | PAS - GDANSK DIVISION |
pp. 143-152, vol. 15, 2012 Jacek Marszal Gdansk University of Technology, Faculty of Electronics , Telecomunications and Informatics, Department of Marine Electronic Systems, Gdansk, Poland Roman Salamon Gdansk University of Technology, Faculty of Electronics, Telecommunication and Informatics, Department of Marine Electronic Systems, Gdansk, Poland Lech Kilian Gdansk University of Technology, Faculty of Electronics, Telecommunication and Informatics, Department of Marine Electronic Systems, Gdansk, Poland Key words: wide bandwidth; Doppler effect Abstract: Silent sonars are designed to reduce the distance over which their sounding pulses can be detected by intercept sonars. In order to meet this objective, we can use periodical
sounding signals that have low power, a very long duration and wide spectrum. If used in the
silent sonar’s receiver, matched filtration ensures very good detection of motionless or slow
moving targets. However, it is more difficult to detect echo signals of fast moving targets with
Doppler effect causing significant error in target distance measurements. In an effort to find
signals that can better resist Doppler effect, maximum length sequence was tested for its
application in silent sonar. It has an elementary signal which includes linear frequency
modulation. It was demonstrated that the signal produces much better results than those
obtained with simple frequency modulation signals.
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